The present invention relates to seals, and more particularly to radial seals for sealing a space about a rotatable shaft.
Radial shaft seals are generally known and typically include a seal member with an inner circumferential “sealing surface”, which may be provided by an annular lip or a cylindrical portion of the seal member, that is engageable with the exterior surface of a shaft. As the shaft rotates within the seal, the sealing surface remains in sliding contact with the shaft outer surface to prevent the migration of substances (e.g., oil, debris particles) through a sealed space. Typically, to provide sufficient sealing pressure and to account for variations in the shaft and seal dimensions and/or misalignments, such seal assemblies are often provided with a biasing member (e.g., a garter spring) to “force” the seal member into engagement with the shaft.
Further, some seal assemblies are provided with a seal member having a formed surface (e.g., sine wave-shaped) that creates a “pumping effect” to remove any substances that become disposed between the sealing surface and the shaft surface. Typically, such pumping seal assemblies are more costly to manufacture than a conventional “non-pumping” seal assembly due to the additional fabrication necessary to create the pumping effect.